Preparation Of Metal Organic Framework-Ionic Liquid Composite System And Its Application In Desulfurization

The sulfur compounds in fuel oil have certain negative effects on human body,environment and social economy.Therefore,deep desulfurization of gasoline has attracted great attention from all over the world.Compared with other desulfurization technologies,oxidative desulfurization has the advantages of mild reaction conditions,high desulfurization rate,and no need for hydrogenation.This project intends to optimize the catalytic oxidative desulfurization technology based on ionic liquids（ILs）,and improve the catalytic activity and selectivity of the catalyst by immobilizing ionic liquids to metal organic framework materials（MOFs）.The MOFs-acid functionalized ionic liquid composite material was constructed by wet impregnation method.The material has the advantages of large specific surface area,easy modification of MOFs and catalytic properties of ionic liquids,which can synergistic desulfurization effect.Moreover,the mass transfer and separation problems due to the viscosity of the ionic liquid can be effectively solved by the solid-liquid operation.（1）Seven acidic ILs were selected:[PrSO₃HMIm]Cl,[PrSO₃HMIm]HSO₄,[BSO₃HMIm]Cl,[BSO₃HMIm]HSO₄,[HOOCMMIm]Cl,[HOOCEMIm]Cl and[HOOCMMIm]HSO₄ to investigate the effect of different ionic liquids on the carrier in simulated oil.X-[PrSO₃HMIm]HSO₄@MIL-100（Fe）composites with the best desulfurization rate were selected.X-ILs@MIL-100（Fe）composites were synthesized by wet impregnation.The characterizations such as FT-IR,EA,BET and XRD show that[PrSO₃HMIm]HSO₄ was well dispersed into the MIL-100（Fe）channel,and it was also demonstrated that the pore structure of carrier material was not destroyed,the actual loading of the ionic liquid in the composite was obtained by elemental analysis.The optimum conditions for oxidative desulfurization were as follows:ILs loading amount was 1.1 mmol/g;catalyst dosage was 50mg;reaction time was 180 min;temperature was 60 ^oC;ratio of solvent/oil was 1,and ratio of O/S was 25.Under the optimal reaction conditions,the desulfurization rates of simulated oil dibenzothiophene（DBT）,thiophene（T）and benzothiophene（BT）were 99.31%,93.65%and82.81%.The desulfurization rate of the catalyst decreased to 70.49%after 5 cycles.（2）Seven MOFs with relatively small pore sizes,UIO-66,MOF-5（Zn）,MIL-53（Al）,CuBTC,MIL-53（Fe）,MIL-101（Cr）,and MIL-125（Ti）as carrier of composite material to explore the effect of the acidic ionic liquid on the simulated oil catalytic oxidative desulfurization.The catalytic material with the best performance was determined as the X-[PrSO₃HMIm]HSO₄@MIL-125（Ti）synthesized by wet impregnation.The structure,specific surface area and morphology of the catalyst were characterized by FT-IR,BET and XRD.It was proved that[PrSO₃HMIm]HSO₄ was well dispersed into the MIL-125（Ti）channel and the actual loading of the ionic liquid in the composite material could be calculated by elemental analysis.The optimum conditions for oxidative desulfurization were as follows:loading was 0.7 mmol/g,catalyst dosage was 30 mg,reaction time was 90 min,temperature was 30 ^oC,ratio of solvent/oil was 0.2,and ratio of O/S was 10.Under the optimal reaction conditions,the oxidative desulfurization rate of the catalyst for DBT simulated oil can reach 99.14%,and the desulfurization rate of the three sulfur-containing substances was DBT≈BT>T.The active desulfurization rate of the catalyst decreased slightly to 93.83% after 7 cycles.